I own 3 Vita devices: TV, PSP1k and PSP2k.
Get yourself a PSP1k for a supreme display if you can but they are pretty pricey to get new or in unused condition.
A PSP2k is easier to obtain new.
When you get your device all that matters is the firmware. If it is <3.60 you are ready for CFW with its ability to run all Vita and PSP backups. You also get the whole PSP firmware on it with XMB and its plugins if you wish to maintain the PSP-feeling! You can also buy a cheep (<10$) MicroSD adapter and load 200GB of files on it to get going (it only works in CFW though)
If the firmware is above 3.60 there are very limited ways to play PSP games. You have to buy them digitally (a shit ton of them didn't make it into the PSN store) and you must buy a very expensive memory card for it to store the games (64gb are far over 100$).
The hugest problem is to break open the PSP emu inside the PSVita. You have to have the vita on a specific firmware and a specific game bought to load a manipulated save onto it to load other games from that. But to buy that specific game you need the most recent firmware on the vita installed => that means those holes are patched and you cannot use the manipulated saves.
That's about it I think. This is a short summery of a wall of informations. Good luck